Corticotropin releasing factor (CRF) is a 41 amino acid peptide that is the primary physiological regulator of proopiomelanocortin (POMC) derived peptide secretion from the anterior pituitary gland [J. Rivier et al., Proc. Natl. Acad. Sci (USA) 80:4851 (1983); W. Vale et al., Science 213:1394 (1981)]. In addition to its endocrine role at the pituitary gland, CRF is known to have a broad extrahypothalmic distribution in the CNS, contributing therein to a wide spectrum of autonomic behavioral and physiological effects consistent with a neurotransmitter or neuromodulator role in the brain [W. Vale et al., Rec. Prog. Horm. Res. 39:245 (1983); G. F. Koob, Persp. Behav. Med. 2:39 (1985); E. B. De Souza et al., J. Neurosci. 5:3189 (1985)]. There is evidence that CRF plays a significant role in integrating the response in the immune system to physiological, psychological, and immunological stressors, in psychiatric disorders and neurological diseases including depression, anxiety-related disorders and feeding disorders, and in the etiology and pathophysiology of Alzheimer's disease, Parkinson's disease, Huntington's disease, progressive supranuclear palsy and amyotrophic lateral sclerosis, as they relate to the dysfunction of CRF neurons in the central nervous system [J. E. Blalock, Physiological Reviews 69:1 (1989); J. E. Morley, Life Sci. 41:527 (1987); E. B. De Souze, Hosp. Practice 23:59 (1988)].
CRF has been implicated in the etiology of mood disorder, also known as affective disorder. It was shown that in individuals afflicted with affective disorder, or major depression, the concentration of CRF in the cerebral spinal fluid (CSF) is significantly increased. [C. B. Nemeroff et al., Science 226:1342 (1984); C. M. Banki et al., Am. J. Psychiatry 144:873 (1987); R. D. France et al., Biol. Psychiatry 28:86 (1988); M. Arato et al., Biol. Psychiatry 25:355 (1989)]. Furthermore, the density of CRF receptors is significantly decreased in the frontal cortex of suicide victims, consistent with a hypersecretion of CRF [C. B. Memeroff et al., Arch. Gen. Psychiatry 45:577 (1988)]. In addition, there is a blunted adrenocorticotropin (ACTH) response to CRF (i.v. administered) observed in depressed patients [P. W. Gold et al., Am. J. Psychiatry 141:619 (1984); F. Holsboer et al., Psychoneuroendocrinology 9:147 (1984); P. W. Gold et al., New Engl. J. Med. 314:1129 (1986)]. Preclinical studies in rats and non-human primates provide additional support for the hypothesis that hypersecretion of CRF may be involved in the symptoms seen in human depression [R. M. Sapolsky, Arch. Gen. Psychiatry 46:1047 (1989)]. There is also preliminary evidence that tricyclic antidepressants can alter CRF levels and thus modulate the numbers of receptors in the brain [Grigoriadis et al., Neuropsychopharmacology 2:53 (1989)].
CRF has also been implicated in the etiology of anxiety-related disorders. Anxiety disorders are a group of diseases, recognized in the art, that includes phobic disorders, anxiety states, post-traumatic stress disorder and a typical anxiety disorders [The Merck Manual of Diagnosis and Therapy, 16th edition (1992)]. Emotional stress is often a precipitating factor in anxiety disorders, and such disorders generally respond to medications that lower response to stress. Excessive levels of CRF are known to produce anxiogenic effects in animal models [see, e.g., Britton et al., 1982; Berridge and Dunn, 1986 and 1987]. Interactions between benzodiazepine/non-benzodiazepine anxiolytics and CRF have been demonstrated in a variety of behavioral anxiety models [D. R. Britton et al., Life Sci. 31:363 (1982); C. W. Berridge and A. J. Dunn, Regul. Peptides 16:83 (1986)]. Studies using the putative CRF receptor antagonist α-helical ovine CRF (9–41) in a variety of behavioral paradigms demonstrates that the antagonist produces “anxiolytic-like” effects that are qualitatively similar to the benzodiazepines [C. W. Berridge and A. J. Dunn, Horm. Behav. 21:393 (1987), Brain Research Reviews 15:71 (1990); G. F. Koob and K. T. Britton, In: Corticotropin-Releasing Factor: Basic and Clinical Studies of a Neuropeptide, E. B. De Souza and C. B. Nemeroff eds., CRC Press p.221 (1990)]. Neurochemical, endocrine and receptor binding studies have all demonstrated interactions between CRF and benzodiazepine anxiolytics, providing further evidence for the involvement of CRF in these disorders. Chlordiazepoxide attenuates the “anxiogenic” effects of CRF both in the conflict test [K. T. Britton et al., Psychopharmacology 86:170 (1985); K. T. Britton et al., Psychopharmacology 94:306 (1988)] and in the acoustic startle test [N. R. Swerdlow et al., Psychopharmacology 88:147 (1986)] in rats. The benzodiazepine receptor antagonist Ro 15-1788, which was without behavioral activity alone in the operant conflict test, reversed the effects of CRF in a dose-dependent manner while the benzodiazepine inverse agonist FG 7142 enhanced the actions of CRF [K. T. Britton et al., Psychopharmacology 94:396 (1988)]. The use of CRF1 antagonists for the treatment of Syndrome X has also been described in U.S. patent application Ser. No. 09/696,822, filed Oct. 26, 2000, and European Patent Application No. 003094414, filed Oct. 26, 2000. Methods for using CRF1 antagonists to treat congestive heart failure are described in U.S. Ser. No. 09/248,073, filed Feb. 10, 1999, now U.S. Pat. No. 6,043,260 (Mar. 28, 2000).
It has also been suggested that CRF1 antagonists are useful for treating arthritis and inflammation disorders [E. L. Webster et al., J Rheumatol 29(6):1252 (2002); E. P. Murphy et al., Arthritis Rheum 44(4):782 (2001)]; stress-related gastrointestinal disorders [K. E. Gabry et al., Molecular Psychiatry 7(5): 474 (2002),]; and skin disorders [C. C. Zouboulis et al., Proc. Natl. Acad. Sci. 99: 7148 (2002)].
It was disclosed recently that, in an animal model, stress-induced exacerbation of chronic contact dermatitis is blocked by a selective CRF1 antagonist, suggesting that CRF1 is involved in the stress-induced exacerbation of chronic contact dermatitis and that CRF1 antagonist may be useful for treating this disorder. [K. Kaneko et al., Exp Dermatol 12(1): 47 (2003)].
EP1085021 discloses pyrrolo[1,2-b]pyridazine compounds as sPLA2 inhibitors. The following publications each describes CRF1 antogonist compounds; however, none disclose the specific compounds provided herein: WO 98/08847 (International Publication Date 5 Mar. 1998); WO 02/072101 (International Publication Date 19 Sep. 2002); WO 02/072202 (International Publication Date 19 Sep. 2002).
It is an object of the invention to provide novel pyrrolo[1,2-b]pyridazine derivatives, which are CRF1 receptor antagonists.
It is another object of the invention to provide novel compounds as treatment of disorders or conditions that are associated with CRF or CRF1 receptors, such as anxiety disorders, depression, and stress related disorders.
It is another object of the invention to provide a method of treating disorders or conditions that are associated with CRF or CRF1 receptors, such as anxiety disorders, depression, and stress related disorders.
It is yet another object of the invention to provide a pharmaceutical composition useful for treating disorders or conditions that are associated with CRF or CRF1 receptors, such as anxiety disorders, depression, and stress related disorders.
There are other objects of the invention which will be evident or apparent from the description of the invention in the specification of the application.